Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and several other medical conditions. Implantable neurological stimulation systems generally have an implantable pulse generator and one or more electrode leads that deliver electrical pulses to neurological tissue or muscle tissue. For example, several neurological stimulation systems for spinal cord stimulation (SCS) have cylindrical leads that include a lead body with a circular cross-sectional shape and one or more conductive rings spaced apart from each other at the distal end of the lead body. The conductive rings operate as individual electrodes. In many cases, the SCS leads are implanted percutaneously through a large needle inserted into the epidural space, with or without the assistance of a stylet. One concern of such leads is that the leads may not remain in the desired position after being implanted. This is undesirable because, if the leads migrate from the initial implantation site, the stimulation provided by the electrodes may no longer be directed to the appropriate target tissue. Accordingly, the efficacy of the treatment can be significantly compromised.
Another type of stimulation lead is a paddle lead. Paddle leads typically have a relatively flat body with electrodes arranged on one side of the body. Paddle leads are commonly used for cortical stimulation and SCS applications. Large paddle leads are desirable because they cover more neurological structures and, in at least some cases, may be more stable and less subject to migration than cylindrical leads. However, large paddle leads are not well suited to percutaneous implantation. As a result, large paddle leads are often surgically implanted using highly invasive procedures that are costly and can lead to patient complications.
One approach to addressing the potential for lead migration is to provide structural reinforcement in one or more portions of the lead, as disclosed in U.S. Pat. No. 7,146,222. However, this approach is principally directed to brain implants, and may not be effective for implantation at other sites, including the spinal cord. Accordingly, there remains a need for improved stimulation devices that resist migration.